class RuboCop::Cop::Style::Proc

would be more appropriate.
This cops checks for uses of Proc.new where Kernel#proc

def autocorrect(node) 

def autocorrect(node)
  ->(corrector) { corrector.replace(node.source_range, 'proc') }
end

def on_block(node) 

def on_block(node)
  proc_new?(node) do |block_method|
    add_offense(block_method, :expression)
  end
end